(a) Field of the Invention
The present invention relates to a method and device for measuring a location of a terminal.
(b) Description of the Related Art
There are various location determination technologies using a radio infrastructure depending on infrastructure types and service ranges.
A global navigation satellite system (GNSS) is a system for determining a location of a user by using a signal of a satellite in orbit of the earth. The GNSS provides high location accuracy having an error of location information within 10 m and availability in the case of level ground or suburbs acquiring a direct line of sight of a satellite and a receiver. On the contrary, in the case of the urban areas that is a non-line of sight area, the error of location information is substantially 50 meters because of multipath errors, and particularly, in the case of a room, received signal sensitivity is deteriorated such that the GNSS cannot determine a location.
A cellular-based location determination technology determines a user's location by using location information of a mobile communication base station and a measured signal, and it can be classified as cell-ID, enhanced-observed time difference (E-OTD), and advanced-forward link trilateration (AFLT) according to the number of base stations available for a terminal. The cellular-based location determination technologies have a merit of determining the location in a room as well as outside the room because of the characteristics of the mobile communication infrastructure having urban areas and most suburban areas as a service range. However, since accuracy of location determination depends on how the base station is disposed and the error of location information is 100 to 800 meters on the average, it is inappropriate for indoor and exterior navigation service requiring location accuracy.
The wireless LAN (local area network)-based location determination technology is a representative method for overcoming the difficulty of indoor location determination, and it calculates the location of a terminal by using a database including an identifier and a reference location of an access point (AP) and a measured value of the AP received from the terminal. That is, the wireless LAN-based location determination technology extracts the AP that has the same identifier as the identifier of the AP for the measured value from the database, and determines the location of the terminal by using the extracted AP. However, when the service area is enlarged and the database is built in a vast manner, it is required to compare the identifier of the AP for the measured value and the identifier of all the AP's of the database, and hence, it takes much time to search the database, location calculation is resultantly slowed, and it is inappropriate for a service that requires a quick response.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.